Benedet AL, Milà-Alomà M, Vrillon A, et al. - Findings demonstrate plasma glial fibrillary acidic protein (GFAP) as a sensitive biomarker with significantly better performance than cerebrospinal fluid (CSF) GFAP in indicating amyloid-β (Aβ) pathology in the early stages of Alzheimer disease (AD).

• In this cross-sectional study, a total of 300 TRIAD (Translational Biomarkers in Aging and Dementia) participants (people in the entire AD continuum), 384 ALFA+ (Alzheimer’s and Families study) participants (individuals with preclinical AD), and 187 BioCogBank Paris Lariboisière participants (individuals with symptomatic AD) were included.

• In the preclinical and symptomatic stages of AD, increased plasma GFAP levels were detected, with levels higher than those of CSF GFAP.

• The accuracy of plasma GFAP was higher than that of CSF GFAP to distinguish between Aβ–positive and Aβ-negative individuals, also at the preclinical stage.